Photoelectric light-curves have been obtained in the visual and in the infrared spectral regions for the eclipsing variable YY Geminorum. Relative and absolute elements, with their probable errors, derived from the light-curves and available spectrographic data, are in good agreement with elements derived by other investigators. Absolute limb-darkening coefficients could not be derived, but it was found that the darkening coefficient in the visual region is greater than that in the infrared by 0.3. Secondary light-variations of considerable amplitude were found during the course of the observing. A study of the photometric and spectrographic data leads to the conclusion that the secondary variations probably are caused by the effects of rotation and eclipse of stellar components with a patchy, nonuniform surface illumination. This conclusion is supported by evidence, discussed in some detail, from three other eclipsing variables.